Condensate removal apparatus



p L 67 I C.D.WARE 3,313,123

CONDENSATE REMOVAL APPARATUS Filed Sept. 2'7, 1965 INVENTOR.

CHESTER D. WARE Jig. 2 BY 2 M 4AM ATTORNEYS United States Patent Office3,313,123 Patented Apr. 11, 1967 3,313,123 CONDENSATE REMOVAL APPARATUSChester D. Ware, La Crosse, Wis., assignor to The Trane Company, LaCrosse, Wis., a corporation of Wisconsin Filed Sept. 27, 1965, Ser. No.490,451 11 Claims. (Cl. 62-272) This invention relates to refrigerationand cooling apparatus and more particularly to means for effectively removing condensate from a fin-and-tube type heat ex-' a heat exchangercoil with a staggered fin edge on the leaving side of the coil.Specifically my invention comprises in combination a heat exchanger coilhaving an entering face and a leaving face; means for passing a streamof vapor containing gas from said entering face through said coil tosaid leaving face; said coil including a plurality of first and secondfins arranged in face-toface relationship; each of said fins having aleaving edge disposed adjacent and substantially parallel to saidleaving face; means for cooling said fins below the dewpoint of saidvapor; over at least a substantial area of said leaving face, theleaving edges of said second fins being disposed downstream of theleaving edges of said first fins whereby condensate collected at theleaving edges of said first fins is transferred to the portions of saidsecond fins disposed downstream of the leaving edges of said first finswhere said condensate imposes little resistance to the passage of saidgas through said coil.

It is a prime object of my invention to provide in a coolingfin-and-tube type heat exchanger means to reduce condensate carryoverwhen operated under dehumidifying conditions.

It is a further object to provide means of reducing the pressure dropacross a fin type heat exchanger caused by excessive accumulation ofcondensate. These and other objects will become more apparent as thisspecification proceeds to describe this invention with reference to thedrawings in which:

FIGURE 1 is a schematic view of a refrigeration system incorporating myinvention; and

FIGURE 2 is an enlarged section taken at line 22 of FIGURE 1 showing aportion of the heat exchanger coil thereof.

Referring to the drawing, a refrigeration circuit is shown as having arefrigerant compressor 10, a refrigerant condenser 12 connected to thedischarge of compressor 10, a refrigerant expansion valve 14 connectedto the outlet of condenser 12, and a refrigerant evaporator 16 connectedto receive liquid refrigerant from valve 14 and to discharge vaporizedrefrigerant to the inlet of compressor 10.

Evaporator 16 includes a fin-and-tube heat exchange coil 18 having anentering face 20 and a leaving face 22. A fan 24 is arranged to passmoisture containing air through coil 18 from face 20 to face 22. Ashroud 26 may be provided to direct the air from fan 24 to coil 18. Acondensate drain pan 28 may be provided to collect condensate drainedfrom the leaving face of coil 18.

Coil 18 is comprised of a plurality of generally planar metallic fins 30of rectangular configuration disposed in spaced face-to-facerelationship.

A plurality of tubes 32 extend perpendicularly through fins 30. Fins 30may be connected to tubes 32 in any well known manner to provide athermal conducting joint for transmission of heat from the fins to thetubes. The tubes 30 are appropriately connected at their ends as byU-bends 34 for providing a continuous refrigerant circuit from valve 14to compressor 10. It should be understood that cooling media other thana refrigerant may be circulated through tubes 32 such as for examplechilled water. Furthermore, other arrangements of the tubes may beemployed without departing from the spirit of my invention.

Certain fins 36 of fins 30 have leaving edges 38 which are disposeddownstream of the leaving edges 40 of other adjacent fins 42 of fins 30.The leaving edges 38 and 46 are vertically disposed. Fins 30 are spacedsufficiently close to enable condensate droplets to bridge between pairsof fins and permit condensate to be transferred from the surface of onefin to the surface of another fin.

During operation of the refrigerant system, compressor 10 compressesrefrigerant and delivers it in a hot gaseous state to condenser 12whereupon it is cooled and condensed to a liquid. The liquid refrigerantfrom condenser 12 is throttled to a lower pressure by valve 14 into coil18. Evaporation of the liquid refrigerant within the tubes 32 of coil 18cools fins 30 below the dewpoint of air passing thereover via fan 24.The evaporated refrigerant then flows to the suction side of compressor10 for recirculation.

Since the fins 30 are cooled below the dewpoint of the air, moisture iscondensed from the air along surfaces between the fins. The flow of airmoves condensate droplets to the leaving face 22 of the coil. Dropletswhich reach the leaving edges 40 of fins 42 transfer to the portions 44of fins 36 downstream of the leaving edges 40 thereof. Since portions 44are free of notches, holes and attachments, they provide ideal paths forthe condensate to flow freely downward into drain pan 28 withoutentraining condensate in the air passing over the fins. Furthermore,tests show that the pressure drop across the fins is materially reducedwhen a staggered leaving fin edge in accordance with this invention isemployed.

While it is not clearly understood why my invention improves thecondensate drainage and pressure drop characteristics of a fin-and-tubecooling coil, several reasons have been postulated. Condensate whichbridges between fins may tend to hang up within the coil because of theadhesion forces presented by the fin surfaces on each side of thecondensate droplets. In my invention the condensate droplets arepermitted to move on to the extended portion of certain fins where theforce of adhesion acts on only one side of the droplets.

Since this single force is insuflicient to uphold the droplets, thecondensate runs freely downward along the extended fin portions. It isalso thought that the maximum air velocity at the leaving face of a coilincorporating my invention is lower than that in a coil of conventionaldesign which may also attribute to the desirable drainagecharacteristics.

Although I have described in detail the preferred embodiment of myinvention, I contemplate that many changes may be made without departingfrom the scope or spirit of my invention, and I desire to be limitedonly by the claims.

I claim:

1. In combination a heat exchanger coil having an entering face and aleaving face; means for passing a stream of vapor containing gas fromsaid entering face through said coil to said leaving face; said coilincluding a plurality of first and second fins arranged in face-to-facerelationship; each of said fins having a leaving edge disposed adjacentand substantially parallel to said leaving face; means for cooling saidfins below the dewpoint of said vapor; over at least a substantial areaof said leaving face, the leaving edges of said second fins beingdisposed downstream of the leaving edges of said first fins wherebycondensate collected at the leaving edges of said first fins istransferred to the portions of said second fins disposed downstream ofthe leaving edges of said first fins where said condensate imposeslittle resistance to the passage of said gas through said coil.

2. The apparatus as defined by claim 1 wherein said leaving edge of eachof said second fins encompassed by said area extends vertically, wherebycondensate accumulated at the leaving edges of said second fins flowsdownwardly therealong with reduced carryover into the stream of saidgas.

3. The apparatus as defined by claim 2 wherein said leaving edge of eachof said second fins encompassed by said area is substantially vertical.

4. The apparatus as defined by claim 1 wherein alternate adjacent finsof said coil are of said first and second fin construction respectively.

5. The apparatus as defined by claim 1 wherein the entering edges ofsaid first and second fins are disposed in a common plane.

6. In combination a heat exchanger coil having an entering face and aleaving face; means for passing a stream of vapor containing gas fromsaid entering face through said coil to said leaving face; said coilincluding a plurality of fins arranged in face-to-face relationship;each of said fins having a leaving edge disposed adjacent andsubstantially parallel to said leaving face; means for cooling said finsbelow the dewpoint of said vapor; over at least a substantial 'area ofsaid leaving face, the leaving edge of each of certain of said finsbeing disposed upstream of the leaving edge of other of said fins nextadjacent thereto whereby condensate collected at the leaving edges ofsaid other of said fins is transferred to the portions of said certainfins disposed downstream of the leaving edges of said other fins wheresaid condensate imposes little resistance to the passage of said gasthrough said coil.

7. The apparatus defined by claim 6 wherein said leaving edge of each ofsaid other fins encompassed by said area extends vertically, wherebycondensate accumulated at the leaving edges of said other fins flowsdownwardly therealon'g with reduced carryover into the stream of saidgas.

8. The apparatus as defined by claim 7 wherein the leaving edge of eachof said other fins encompassed by said area is substantially vertical.

9. The apparatus as defined by claim 6 wherein the entering edges ofsaid certain and other fins are disposed in a common plane.

10. Incombination a heat exchanger coil having an entering face and avertically extending leaving face; means for passing a stream of vaporcontaining gas from said entering face through said coil to said leavingface; said coil including a plurality of first and second verticallyextending fins arranged in fact-to-face relationship; said fins beingspaced sufficiently close at the leaving face of said coil to permitcondensate to transfer from one fin to the next adjacent fins, each ofsaid second fins being provided with a condensate drain path disposeddownstream of the leaving edge of said first fins; each of said drainpaths comprising a portion of one of said second fins extendeddownstream of the leaving edges of said first fins; said downstreamextended portion being continuous throughout its length to permit freeuninterrupted fiow of condensate from the leaving face of said coil.

11. Heat exchange apparatus comprising a fin-and-tube type heatexchanger coil having a plurality of generally planar first finsinterleaved with a plurality of generally planar second fins inface-to-face relationship and arranged in such proximity as to permitliquid condensate to bridge between said first and second fin; means forpassing a stream of vapor containing gas from the front face of saidcoil through said coil between the fins thereof, to the rear face ofsaid coil; each of said first and second fins having a verticallyextending rear edge disposed rearwardly of the rearmost tube of saidcoil and extending generally parallel to the rear face of said coil;means for passing a cooling fluid through the tubes of said coil ofsufficiently low temperature to cool said fins below the dewpoint ofsaid vapor; said rear edges of said second fins being disposedrearwardly of said rear edges of said first fins whereby condensatecollected at the reared-ge of said first fins is transferred to theportions of said second fins disposed rearwardly of the rear edgesReferences Cited by the Examiner UNITED STATES PATENTS 1,975,066 9/1934Sanderson 62-285 2,613,065 10/1952 Didier 16 5146 WILLIAM J. WYE,Primary Examiner.

1. IN COMBINATION A HEAT EXCHANGER COIL HAVING AN ENTERING FACE AND ALEAVING FACE; MEANS FOR PASSING A STREAM OF VAPOR CONTAINING GAS FROMSAID ENTERING FACE THROUGH SAID COIL TO SAID LEAVING FACE; SAID COILINCLUDING A PLURALITY OF FIRST AND SECOND FINS ARRANGED IN FACE-TO-FACERELATIONSHIP; EACH OF SAID FINS HAVING A LEAVING EDGE DISPOSED ADJACENTAND SUBSTANTIALLY PARALLEL TO SAID LEAVING FACE; MEANS FOR COOLING SAIDFINS BELOW THE DEWPOINT OF SAID VAPOR; OVER AT LEAST A SUBSTANTIAL AREAOF SAID LEAVING FACE, THE LEAVING EDGES OF SAID SECOND FINS BEINGDISPOSED DOWNSTREAM OF THE LEAVING EDGES OF SAID FIRST FINS WHEREBYCONDENSATE COLLECTED AT THE LEAVING EDGES OF SAID FIRST FINS ISTRANSFERRED TO THE PORTIONS OF SAID SECOND FINS DISPOSED DOWNSTREAM OFTHE LEAVING EDGES OF SAID FIRST FINS WHERE SAID CONDENSATE IMPOSESLITTLE RESISTANCE TO THE PASSAGE OF SAID GAS THROUGH SAID COIL.